CN101398493A - Amplitude type zone plate photonsieve - Google Patents

Abstract

The invention discloses an amplitude-typed zone plate photon sieve, belonging to the field of optical instruments. The amplitude-typed zone plate photon sieve is arranged on a transparent medium; wherein, the central position thereof is provided with a Fresnel zone plate girdle; the periphery of the girdle is provided with normal photon sieve round holes; the round holes of the photon sieve surround the girdle of the zone plate; wherein, the Fresnel zone plate is an amplitude type; the design parameter of the zone plated based on the prepared photon sieve and the design parameter of the zone plate surrounded inwardly are consistent; the diameter of each round hole of the photon sieve is 1.5 times of the girdle at corresponding position; the diameter of the most-external round hole at the peripheric photon sieve is consistent to the width of the most-external girdle of the zone plate at the central position; the diameters are determined according to the process capability of the existing finely processed minimum linewidth. The amplitude-typed zone plate photon sieve can be used for beam shaping, microelectronic maskless etching, strong laser energy concentration, X-ray focusing and various other instruments where energy is needed to focus to the central facula, can improve the sieve focusing diffraction intensity, thus improving the main facula energy of the laser beam far field diffraction facula.

Description

Amplitude type zone plate photonsieve

Technical field

The present invention relates to shaping technique field, a kind of laser beam corrugated, particularly relate to a kind of amplitude type zone plate photonsieve.

Background technology

So-called photon screen is a kind of novel focal imaging diffraction optical device, utilizes it to focus on and imaging X-ray, and this is that the image optics device of general prism and glass material can't be realized.Photon screen is compared with traditional optical element Fresnel Fresnel zone plate, has advantages such as high resolving power and inhibition second-order diffraction principal maximum, can improve the contrast of imaging.And, as novel diffraction element, advantages such as volume is little, in light weight, transreplication that it has.

Photon screen can be applied to high resolution microscope, astronomical telescope, photoetching of future generation, the controlled nuclear fusion of laser (ICF) research etc.

In calendar year 2001, Kipper et al. has proposed a kind of novel diffraction optical device first: photon screen can focus on and imaging [Kipp grenz ray and EUV radiating light source with it, L., Skibowski, M., Johnson, R.L., Berndt, R., Adelung, R., Harm, S., and Seemann, R.Sharper images by focusing soft X-ray withphoton sieves.Nature[J], 2001.414,184-188.].

Gil and Menon in 2003 is reported in " beam flying photoetching " and (ZPAL) substitutes zone plate [Menon with photon screen in the system, R., Gil, D.Barbastathis, G., and Smith, H.I.Photon-sieve lithography[J] .Opt.Soc.Am.A, 2005.22 (2), 342-345.].

After this, because the superior performance that photon screen itself has, people are more and more interested in it, and it is applied to various new research fields, as EUV telescope around solar satellite, [S.Wang andX.Zhang.Terahertz tomographic imaging with a Fresnel lens[J] .Opt.Photon.2002.News13 such as THZ ripple holography, 59].

Photon screen (Photon Sieve, PS) be the diffraction optical elements of on the Fresnel zone ring, making a large amount of transparent micropores that suitably distribute with different radii (Diffraction Optical Element, DOE).

Photon screen has good application in the focusing of grenz ray, extreme ultraviolet line and imaging, can be applicable to fields such as high resolving power microscopy, spectroscopy, photoetching of future generation.Replace fresnel's zone plate Fresnel zoneplate (FZP) that grenz ray is focused on and imaging with photon screen (PS), can obtain higher resolution, reduce requirement the photoetching technique manufacture craft.But the hot spot mainboard energy that photon screen focuses on can be done further lifting.

The parameter that is used to weigh diffracting effect comprises " central energy than " and " first zero ".Our definition " central energy than " be the energy of the energy of diffractional field central authorities main lobe divided by whole diffractional fields.It can characterize central main lobe energy concentration degree." first zero " of definition is the position at the energy-minimum place between the main lobe and first secondary lobe, and its position can characterize the size of central main lobe.

Summary of the invention

Fundamental purpose of the present invention is to provide a kind of amplitude type zone plate photonsieve, with the lifting again of the main spot energy of realizing laser beam far field construction spot.For achieving the above object, technical scheme of the present invention is as follows:

Amplitude type zone plate photonsieve of the present invention, comprise the fresnel's zone plate endless belt on the described amplitude type fluctuation sheet, outer periphery at described fresnel's zone plate endless belt is equipped with photon screen circular hole endless belt, promptly according to the design parameter of fresnel's zone plate, the peripheral endless belt of described fresnel's zone plate is replaced with photon screen circular hole endless belt; The diameter of described photon screen circular hole is 1.5 times of the described fresnel's zone plate endless belt width that substituted; The diameter of the outer shroud circular hole of described photon screen is consistent with the width of described fresnel's zone plate outermost endless belt.

Amplitude type zone plate photonsieve of the present invention, described fresnel's zone plate are amplitude type.

Amplitude type zone plate photonsieve of the present invention, described amplitude type zone plate photonsieve is made by transparent medium.

Amplitude type zone plate photonsieve of the present invention, the width of the outer shroud endless belt of described fresnel's zone plate is more than or equal to the minimum feature of existing processing technology ability.

The beneficial effect of technical scheme provided by the invention is: amplitude zone plate photon sieve provided by the invention, by the circular hole of the center section of common photon screen diffraction is changed into fresnel's zone plate, make collimation parallel laser form of the center master spot energy raising of center master's spot in the far field than photon screen diffraction by the amplitude zone plate photon sieve, but the optical field distribution that the main lobe size does not significantly increase.The present invention combines the high-diffraction efficiency of fresnel's zone plate and emerging photon screen, realized that photon screen focuses on the light distribution that the main spot energy of diffraction improves again, promptly realized the raising again of the main spot energy of laser beam far field construction spot, this be traditional photon screen can't realize.

Description of drawings

Fig. 1 is existing 50 ring photon screen synoptic diagram;

Fig. 2 is the structural representation of amplitude type zone plate photonsieve embodiment 108 ring amplitude zone plate photon sieves of the present invention;

Fig. 3 is the diffraction intensity of the embodiment of the invention 108 ring amplitude zone plate photon sieves and the comparison diagram of existing 108 common photon screen diffraction intensities of ring and radial distance;

Fig. 4 is the experiment pick-up unit figure of amplitude zone plate photon sieve of the present invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.

Existing zone plate alternately is made up of transparent and opaque annulus, in order to stop odd number band or the even number band in the fresnel zone.Under spot light, can obtain high-intensity picture point through it.The radius of zone plate is pressed during making $[55-08]{\mathrm{\ρ}}_k=\sqrt{{\mathrm{k\ρ}}_1},$ =1,2, the delineation of 3... ratio again with the blacking of odd number (or even numbers) wavestrip, only allows even numbers (or odd number) wavestrip open.When this sheet of planar zone plate of parallel light, be at the distance zone plate $[55-09]f={\mathrm{\ρ}}_1^2/\mathrm{\λ}$ A prime focus (diffraction gathering) is arranged, and its light intensity can reach freely propagates more than hundreds and thousands of times of light intensity.

Existing photon screen is a diffraction optical element of making a large amount of transparent micropores with different radii that suitably distribute on the Fresnel zone ring.

By the conclusion of diffraction optics angular spectrum as can be known:

Be located at and introduce an infinitely-great opaque screen that includes the photon screen structure on the z=0 plane, desirable plane wave impinges upon on the photon screen.The transmittance function of photon screen is:

$E(x,y,0)=\left\{\begin{array}{cc}1& {(x-x_{\mathrm{ij}})}^2+{(y-y_{\mathrm{ij}})}^2\≤{r_i}^2\\ 0& \mathrm{other}\end{array}---\left(1\right)\right.$

In (1), xij, yij represent micropore central coordinate of circle on the wavestrip, i=1, and 2......n, (n is the zone plate number of rings) j=1,2 ... m (m is the number cells on the respective rings).Discrete Fourier transformation obtains the angular spectrum F0 (fx, fy, 0) of incident light on diffraction screen to E (x, y, 0) through two-dimensional space.

$E(f_x,f_Y.0)=\underset{-\∞}{\overset{\∞}{\∫}}\underset{-\∞}{\overset{\∞}{\∫}}E(x,y,0)\exp [-j2\mathrm{\π}(f_{X}x+f_{Y}y)]\mathrm{dxdy}---\left(2\right)$

In (2), f _X, f _YBe spatial frequency, $f_X=\frac{\mathrm{\α}}{\mathrm{\λ}},$ $f_Y=\frac{\mathrm{\β}}{\mathrm{\λ}}$ (α, β are wave vectors

With X-axis, the angle between the Y-axis).Incident light is propagated along the z direction through behind the photon screen.At the Z=z place, the frequency spectrum E. of spatial frequency (fx, fy z) are:

$E(f_X,f_Y,z)=E(f_X,f_Y,0)\exp (j2\mathrm{\π}\sqrt{\frac{1}{{\mathrm{\λ}}^2}-f_X^2-f_Y^2}.z)---\left(3\right)$

In (3), f _Xf _YMust satisfy condition $f_X^2+f_Y^2\≤1/{\mathrm{\λ}}^2,$ This formula shows that the effect of propagating the z of a segment distance has just changed the relative phase of each angular spectrum component.But work as $f_X^2+f_Y^2>1/{\mathrm{\λ}}^2$ The time, (fx, fy z) are the frequency spectrum E. of spatial frequency

E(f _X，f _Y，z)＝E(f _X，f _Y，0)exp(-μz) (4)

In (4), $\mathrm{\μ}=\frac{2\mathrm{\π}}{\mathrm{\λ}}\sqrt{{\left(\frac{x}{z}\right)}^2+{\left(\frac{y}{z}\right)}^2-1}.$

Because μ is an arithmetic number, these wave components increase decay rapidly because of propagation distance.(4) formula is done inverse Fourier transform, obtain light wave amplitude E (x, y, z)

$E(x,y,z)={\∫}_{-\∞}^{\∞}{\∫}_{-\∞}^{\∞}E(f_X,f_Y,0)\exp (j2\mathrm{\π}\sqrt{\frac{1}{{\mathrm{\λ}}^2}-f_X^2-f_Y^2}.z)\exp \left[j2\mathrm{\π}(f_{X}x+f_{Y}y)\right]{\mathrm{df}}_X{\mathrm{df}}_Y---\left(5\right)$

It more than is the diffraction theory of common photon screen.And at amplitude type zone plate photonsieve, what need modification is exactly each transmittance function.Become circular hole by the circular aperture of complete printing opacity and add annulus amplitude type diffraction element.

Amplitude type zone plate photonsieve of the present invention is that the basic structure improvement that combines existing photon screen and Fresnel zone ring forms.This amplitude zone plate photon sieve provided by the invention, be that a slice is on transparent medium, make common fresnel's zone plate earlier, and at the common photon screen of the peripheral manufacturing of zone plate, the circular hole of photon screen surrounds zone plate, promptly surrounds the endless belt of endless belt replacement zone plate with the circular hole of photon screen in the periphery of zone plate.Like this, the core of amplitude type zone plate photonsieve of the present invention is existing Fresnel zone ring, and the periphery of Fresnel zone ring is processed to the circular hole endless belt form of existing photon screen.Fresnel's zone plate among the present invention is an amplitude type.The photon screen institute that makes based on zone plate the same with the zone plate parameter that inside is surrounded.The diameter that is each aperture in the peripheral photon screen is 1.5 times of the corresponding Fresnel zone ring endless belt width that is replaced.The width of the outer shroud endless belt of the diameter that will guarantee the outer shroud aperture of the peripheral photon screen of the present invention by design and core fresnel's zone plate of the present invention is consistent, they all are subject to microfabrication and get minimum feature, so when design amplitude type zone plate photonsieve of the present invention, also will consider existing processing technology ability.The fresnel's zone plate annulus of core and the common formation of the photon screen circular hole that surrounds on every side amplitude type zone plate photonsieve of the present invention.

Amplitude type zone plate photonsieve with one 108 ring is an example below, describes its method for making:

1,, determines photon screen focal length and number of rings according to optical maser wavelength and existing processing technology ability according to existing photon screen method for designing;

2, the common fresnel's zone plate at machining center position;

3, the photon screen of processing Fresnel zone plate periphery.

Suppose that optical maser wavelength is 6328 nanometers, focal length is 100 millimeters, and number of rings is 108 rings.Wherein the number of rings of zone plate is 50, and the diameter of the outer shroud circular hole of periphery photon screen among the width of doing the outer shroud of fresnel's zone plate that can guarantee the centre among the present invention like this and the present invention is identical.Because the processing technology ability is in the continuous conversion with the development of optical technology, suppose that here the live width of making is 18.2 microns.The circular hole of supposing the periphery photon screen is at fresnel's zone plate even number endless belt, and then the radius of little circular hole is from big to small:

52.0988 micron, 33.7020 microns, 26.8437 microns, 22.9765 microns, 20.4109 micron, 18.5493 microns, 17.1191 microns, 15.9758 microns, 15.0348 micron, 14.2427 microns, 13.5639 microns, 12.9737 microns, 12.4544 micron, 11.9929 microns, 11.5792 microns, 11.2055 microns, 10.8658 micron, 10.5553 microns, 10.2699 microns, 10.0065 microns, 9.7624 micron, 9.5353 microns, 9.3234 microns, 9.1250 microns.

And the position of the fresnel's zone plate annulus in centre of the present invention is at odd loop, and its position is respectively: 0.3558-0.4357 millimeter, 0.5031-0.5625 millimeter, 0.6162-0.6656 millimeter, 0.7115-0.7547 millimeter, 0.7955-0.8343 millimeter, 0.8714-0.9070 millimeter, 0.9412-0.9743 millimeter, 1.0062-1.0372 millimeter, 1.0673-1.0965 millimeter, 1.1250-1.1528 millimeter, 1.1799-1.2064 millimeter, 1.2324-1.2578 millimeter, 1.2827-1.3071 millimeter, 1.3311-1.3547 millimeter, 1.3778-1.4006 millimeter, 1.4230-1.4451 millimeter, 1.4668-1.4882 millimeter, 1.5093-1.5302 millimeter, 1.5507-1.5710 millimeter, 1.5910-1.6107 millimeter, 1.6303-1.6496 millimeter, 1.6686-1.6875 millimeter, 1.7061-1.7246 millimeter, the 1.7428-1.7609 millimeter.

Utilize above-mentioned parameter just can carry out the making work of fresnel's zone plate of the present invention.Between above-mentioned every group of two distances is the zone plate annulus of printing opacity, and remaining part is made light tight.Fig. 2 is the synoptic diagram of the 108 ring amplitude type zone plate photonsieve structures of amplitude type zone plate photonsieve embodiment of the present invention, and the black among the figure is lighttight part, and the white among the figure is the part of printing opacity.

Amplitude type zone plate photonsieve of the present invention is a kind of novel diffraction optical device.This device is positioned over before or after the diffraction limit lens, and laser beam far field construction hot spot spectrum light intensities at different levels are revised, and realizes the diffraction center diffraction spot more concentrated than the diffraction center spot energy of common photon screen.The Dan Yuan diffraction aperture that less diffraction circular hole that amplitude type zone plate photonsieve of the present invention adopts and diffraction ring structure replace common photon screen.The present invention has provided the project organization of circular ring diffraction unit, and has carried out relevant simulated experiment.Experimental verification adopt amplitude zone plate photon sieve of the present invention can realize the further lifting of laser beam far field main spot energy.The technology of the present invention can be used for beam shaping, microelectronics non-mask etching, light laser concentration of energy, and X ray focuses on and other needs energy focusing in the various instruments of center spot.

Describing amplitude type zone plate photonsieve parameter of the present invention has and comprises:

1) central energy of zone plate photon sieve ratio: promptly Zhun Zhi coherent light passes through girdle photon sieve, in the diffractional field that is produced, and the energy ratio of main spot and total diffractional field.Ratio is high more, illustrates that the energy of main spot gathering is many more.

2) first zero of zone plate photon sieve: the first zero is minimizing position between the main spot and first diffraction maximum.Be worth greatly more, illustrate that main spot chassis is big more.Be worth more for a short time, illustrate that main spot chassis is more little.

The design parameter of the amplitude zone plate photon sieve that provides according to the embodiment of the invention.We have provided the comparison curves of diffraction intensity in Fig. 3.We have selected the common photon screen of existing 108 rings and the amplitude type zone plate photonsieve of the present invention of 108 rings to compare.The reason of Xuan Zeing is that this two device has identical minimum diffraction element size like this, promptly identical minimum outer shroud radius and smallest circle hole dimension.Compared by display centre energy among Fig. 3: existing common photon screen is 0.9592, and first zero position is 9; The central energy ratio of amplitude type zone plate photonsieve of the present invention is 0.9691, and first zero position is 9; Simultaneously, under identical incident light situation, the diffraction intensity peak value of amplitude type zone plate photonsieve of the present invention is 2 times of existing common photon screen approximately, and this has greatly increased the luminous energy of diffractional field.

Table 1 is depicted as the diffraction comparative result of above-mentioned two kinds of devices.

By comparative result as seen, the central energy of existing common photon screen ratio is 0.9592, and amplitude type zone plate photonsieve of the present invention lifting by a relatively large margin main spot diffraction intensity peak value, and make encircled energy increase.

	Based on fresnel's zone plate number of rings (F)	The central energy ratio	The first zero
				Amplitude type zone plate photonsieve	108	0.9691	9
Common photon screen	108	0.9592	9

Table 1

Amplitude zone plate photon sieve of the present invention in the application of reality as shown in Figure 4.The 1st, collimation laser device, the 2nd, condenser lens, the 3rd, amplitude type zone plate photonsieve of the present invention, the 4th, CCD photodetector.Light process condenser lens 2 and amplitude type zone plate photonsieve 3 from collimation laser 1 sends produce main spot diffractogram on the focal plane of condenser lens 2.Such diffraction master spot intensity distributions can be detected and confirmed it by the ccd detector on the focal plane that is placed on condenser lens 24.

After experimental results show that adding amplitude zone plate photon sieve of the present invention, realized of the further lifting of far field construction hot spot main lobe energy really than the main spot energy of common photon screen.This proves absolutely that the present invention can be used for beam shaping, microelectronics non-mask etching, light laser concentration of energy, and x ray focusing and other need energy focusing in the various instruments of center spot.

The above only is preferred embodiment of the present invention, and is in order to restriction the present invention, within the spirit and principles in the present invention not all, any modification of being done, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (4)

1, a kind of amplitude type zone plate photonsieve, comprise the fresnel's zone plate endless belt on the described amplitude type fluctuation sheet, it is characterized in that, outer periphery at described fresnel's zone plate endless belt is equipped with photon screen circular hole endless belt, promptly according to the design parameter of fresnel's zone plate, the peripheral endless belt of described fresnel's zone plate is replaced with photon screen circular hole endless belt; The diameter of described photon screen circular hole is 1.5 times of replaced described fresnel's zone plate endless belt width; The diameter of the outer shroud circular hole of described photon screen is consistent with the width of described fresnel's zone plate outermost endless belt.

2, amplitude type zone plate photonsieve according to claim 1 is characterized in that, described fresnel's zone plate is an amplitude type.

3, amplitude type zone plate photonsieve according to claim 1 is characterized in that, described amplitude type zone plate photonsieve is made by transparent medium.

4, amplitude type zone plate photonsieve according to claim 1 is characterized in that, the width of the outer shroud endless belt of described fresnel's zone plate is more than or equal to the minimum feature of existing processing technology ability.

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